amj99 Quarterly Rpt. sidebar
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(Quarterly Report for April-May-June 1998)
Participation
in Alaska Department of Fish and Game Gulf of Alaska Seasonality Study
Members of the Resource Assessment
and Conservation Engineering (RACE) Divisions Groundfish Assessment Program
participated in the first phase of a Alaska Department of Fish and Game (ADF&G)
seasonal bottom trawl study of Marmot Bay off Kodiak and Afognak Islands in the Gulf of
Alaska (GOA) 16-25 June aboard the ADF&G research vessel Resolution. The
primary purpose of the study, which includes additional sampling periods scheduled for
August and October 1998 and January, March, and June 1999, is to document seasonal trends
in depth and inshore/offshore distribution of crab and groundfish resources including
Tanner crab (Chionoecetes bairdi),Pacific cod, walleye pollock, arrowtooth
flounder, flathead sole, rock sole, yellowfin sole, and skates. Additionally, the
seasonal nature of the sampling design will provide quantitative measures of changes in
co-occurrence of the demersal groundfish and crab complex, document the changes in
distribution of Pacific cod relative to Federal and state waters, and document
intra-annual changes in the distribution of Tanner crab associated with maturation.
Along with these objectives, the ADF&G invited AFSC scientists to conduct
ancillary studies including specimen collections, food habit studies, research in seasonal
gonad development and size-at-maturity for selected species. The RACE Division
Groundfish Program also recognizes the unique opportunity the seasonality study provides
by introducing ADF&G to standard RACE Division sampling protocol which, if
implemented, would provide data sets from the ADF&G annual crab/groundfish survey of
the western GOA similar to those obtained by the NMFS GOA triennial survey (see
National Marine Fisheries Service/Alaska Department of Fish and Game Trawl
Comparison Study, Quarterly Report, January-February-March
1998). The
Resolution
was subsequently equipped with RACE Division sampling gear including sorting and weighing
tables, electronic length-frequency units, bottom contact sensors,
micro-bathythermographs, and computers and software for length-frequency, catch entry, and
other data collections.
Thirty-one bottom trawl samples were
completed during the seasonality study with the ADF&G standard 400-mesh Eastern survey
trawl at depths ranging from 35 to 250 m. All catches were sampled and
processed to obtain species composition by weight for all components of the catch.
Length frequencies were obtained electronically for all commercial groundfish
species. Additionally, over 200 Pacific cod stomachs and 325 pollock otoliths were
collected for processing at the AFSC. The August seasonality study will continue the
collections begun in June but will expand to include additional species such as flathead
sole and arrowtooth flounder. A reproductive study of Pacific cod and flathead sole
is scheduled to begin during the October phase of the seasonality study.
By Eric Brown and Harold Zenger.
West Coast Shelf
Triennial Trawl Survey
The eighth triennial bottom trawl
survey of groundfish resources of the west coast shelf began on 8 June 1998 aboard the
chartered fishing vessels Vesteraalen and Dominator. Survey
operations began in the vicinity of lat. 34°30N near Point Conception, California.
Sampling will proceed in a northerly direction and will extend as far north, time
allowing, as approximately lat. 49° 30N, off southwest Vancouver Island, British
Columbia. The survey will employ a stratified random design which places
approximately 620 predetermined trawl stations into three depth strata between 55 and 500
m along east-west track lines spaced 10 nautical miles (nmi) apart. The survey will
end in Seattle on August 9.
The objectives of the 1998 survey
will be similar to recent west coast triennial surveys and will be accomplished through a
multi-species assessment approach. Results of the survey will be used to address
current problems being faced by managers and researchers of west coast groundfish stocks.
The objectives of the survey are to:
Describe and assess the demersal
component of the Pacific hake, Merluccius productus, resource
Describe and assess the shallow
water component of the sablefish, Anoplopoma fimbria, resource, specifically those
under 2 years of age
Monitor the abundance,
distribution, and biological characteristics of principal rockfish species,
Sebastes
spp
Monitor the status of other key
groundfish stocks
Collect biological samples from a
variety of commercially important species, including several rockfish, lingcod
(Ophiodon elongatus), and Pacific halibut (Hippoglossus
stenolepis), as well as the
primary target species
Collect temperature profiles to
relate changes in fish distribution among years to changes in oceanographic conditions.
By Russ Nelson.
Annual Bering Sea
Bottom Trawl Survey
The chartered fishing vessels Aldebaran
and Arcturus departed Dutch Harbor, Alaska, on 6 June to conduct a standard bottom
trawl assessment survey of groundfish and crab resources of the eastern Bering Sea shelf.
Trawling operations began at the eastern edge of Bristol Bay and will cover the
eastern Bering Sea continental shelf from inner Bristol Bay to the shelf break, and
between Unimak Pass to north of St. Matthew Island. Upon completion of the standard
bottom trawl survey, the Aldebaran will conduct a trawl survey of Pavlov Bay and
the Arcturus will conduct tests of a towed video system to be used in future
studies of the impact of fishing gear on the seafloor. The Aldebaran and
Arcturus
will complete operations in Dutch Harbor on 13 and 15 August, respectively. The
standard survey consists of approximately 380 sampling stations positioned on a 20-nmi by
20-nmi grid.
The primary objective of the survey
is to continue the annual series of assessment surveys of crab and groundfish resources of
the eastern Bering Sea to provide information for:
The North Pacific Fishery
Management Council on the distribution, abundance, and biological condition of important
groundfish and crab resources
The U.S. fishing industry on
catch-per-unit effort and size composition
The support of ongoing studies of
the biology, behavior, and dynamics of key ecosystem components.
By Russ Nelson.
Trawl Positioning
Gear Trials
Gear trials to evaluate the accuracy
of three ultra-short baseline (USBL) systems which could be used in providing real-time
information on the geographic location of bottom trawls on the seafloor were conducted
aboard the chartered fishing vessel Vesteraalen in Dabob Bay, Hood Canal,
Washington, 18-29 May 1998. Accurate information on trawl location are important to
research on the impacts of fishing gear on the seafloor. The ability to resample
specific areas is essential to experimental work planned for the Bering Sea in future
years.
The primary research objective was
to compare the performance of three acoustic systems that could be used for real-time
positioning of a bottom trawl net. Accuracy of each system will be quantified and
compared through trawling within the U.S. Navys Naval Undersea Warfare Centers
(NUWC) fixed underwater tracking range in Dabob Bay. The Dabob Range is a fixed
short baseline (SBL) hydrophone array operated by the NUWC to test and evaluate weapon
systems, ships, research and development, and fleet training. USBL systems from
three vendors (Kongsberg Simrad, Nautronix, Inc., and ORE International, Inc.) were
installed, calibrated, and tested during the gear trials. Data were
successfully obtained from each of the three systems and are currently being analyzed.
By Russ Nelson.
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